The invention relates to a method of endoscopically injecting at least one fluid and an apparatus with which to implement the method.
During endoscopic operations a great variety of manipulations are undertaken in natural or artificial cavities in the body, in the course of which it repeatedly becomes necessary to remove tissues and/or stop bleeding. Among the techniques used here are forms of injection. For example, a polyp on a sufficiently long stalk can be removed relatively simply (by catching it in a noose), but this is not possible in the case of so-called sessile polyps, which are merely small elevations in the tissue. In such cases it is necessary to raise the polyps, by injecting fluid, in particular physiological saline, into the underlying tissue by means of an injection needle. A sessile polyp raised in this way can then be removed with the known techniques.
A different occasion for the injection of fluids arises when bleeding must be stanched. One way to stop bleeding is to inject physiological saline so as to form a depot around a blood vessel and thereby close it mechanically. Alternatively, a corresponding effect can be achieved by the injection of medications, in particular vasoconstrictive substances. Another means of stopping bleeding is the injection of fibrin adhesives.
Finally, yet another application of injections should be mentioned, namely the marking of operation or treatment sites. Often after a treatment such as the removal of a growth in the intestine, the affected site must be inspected at regular intervals in order to monitor the result of the treatment or the healing process. In particular when the operation site covers a small area and healing is progressing well, it is very difficult to find the treated site again. For this purpose it is useful to stain the treated site or to place marking dots in its vicinity.
The object of the invention is to disclose a method and an apparatus by means of which fluids can be injected during endoscopic operations.
To solve the problem cited above a method is disclosed for the endoscopic injection of at least one fluid, in particular a solution, a suspension or an emulsion or a mixture of several solutions, into a tissue in a hollow organ, a body cavity or an artificial cavity in a human or animal body. In this process a specified amount of fluid is expelled from the end of a tube or from a nozzle with specifiably adjustable hydraulic parameters such as pressure, rate of rise of pressure, duration and velocity of fluid flow, and with energy such that after an essentially free flight across a distance separating the tube end or nozzle from the tissue, the fluid penetrates into the tissue. That is, in the method in accordance with the invention (or in the apparatus in accordance with the invention) no injection needle is used, which would have to be inserted into the tissue to which the liquid is to be applied. This property makes the method in accordance with the invention especially suitable for the application of fluids during endoscopic operations. In particular, the hydraulic parameters can be adjusted so as to ensure that the fluid penetrates the tissue down to a specified depth, at which the fluid can then exert the desired effect. As a result, it also becomes considerably more certain that undesirable effects will be avoided. For instance, when a site in the intestine is to be marked, it is extremely dangerous to operate with an injection needle, because it is very easy to pierce through the intestinal wall. When the method in accordance with the invention is used, this danger is considerably less.
The preferred procedure is not to apply the entire amount of fluid to be injected in a single xe2x80x9cportionxe2x80x9d. Instead, the desired amount of fluid is injected as a plurality of minimal amounts, all of substantially the same size. The result is to ensure that essentially any desired total amount of fluid can be injected, while nevertheless keeping constant the hydraulic parameters, i.e. the parameters that determine the depth of injection, the diameter of the opening formed in the tissue, and so on; the outcome of the injection process is therefore optimal.
The fluid is preferably not injected perpendicularly into the tissue (i.e., perpendicular to its surface), but rather at an angle. This angle is preferably 30xc2x0 to 60xc2x0 with respect to the tissue. Surprisingly, this range has been found to give the best injection results.
Where possible, the fluid is injected in such a thin stream that the hole formed in the tissue during injection closes immediately thereafter, so that practically none of the injected fluid is then released. This can readily be achieved, because when a correspondingly large number of single (individually small) portions is injected, the amount of fluid can be made as large as desired even though the stream of fluid is very thin.
When two different fluids that can react with one another are to be applied, such as the above-mentioned fibrin adhesive or the like, the fluids are preferably not mixed until just before they injected together, or they are injected separately in rapid succession (in small portions as described above) at the same site, in such a way that they become mixed at the injection site. Especially in the case of fluid mixtures, the individual components of which react with one another very rapidly, and in particular solidify or adhere together, this method of successive injection of fluids is an excellent means of preventing a reaction from taking place in the injection apparatus itself (nozzle or end of tube) and hence destroying the apparatus.
A certain problem can be presented by the unintended emergence of fluid from the end of the tube. This is of no importance when the fluid is a physiological saline solution to be injected underneath a polyp. However, if it is a marking fluid such as tattooing ink, accidental leakage from the end of the tube has fatal consequences, because a place is marked that should not be marked at all. It would be equally fatal if medications were to leak out accidentally. However, some leakage cannot be avoided, if only because a tube filled to its distal end and positioned in the working channel of the endoscope changes its volumexe2x80x94although only slightlyxe2x80x94as the endoscope moves, so that some liquid emerges. It is now proposed to suck away fluid that emerges unintentionally from the end of the tube. This action is made particularly simple by generating a continuous suction current, such that the volume it withdraws per unit time is smaller than the volume injected per unit time during the injection process. By this means, it is ensured that the slowly, unintentionally emerging fluid is completely sucked away, whereas the amount of fluid emerging at high velocity, with a relatively high volume flow per unit time, is practically not reduced.
The endoscopic injection apparatus in accordance with the invention, designed to inject at least one fluid, in particular a solution, a suspension or an emulsion or a mixture thereof into a tissue in a hollow organ, a body cavity or an artificial cavity in a human or animal body, comprises a tube with a distal and a proximal end, which can be so inserted through a working channel of an endoscope, or is so incorporated into an endoscope, that the distal end of the tube projects out of a distal end of the endoscope or ends substantially at the end of the endoscope. A pump mechanism is provided that is in sealed connection with the proximal end of the tube and is so constructed that in response to a control signal it expels from the distal end of the tube a specified amount of fluid, with hydraulic parameters such as pressure, rate of pressure increase, duration and/or velocity that can be set to specified values, and with sufficient energy that the fluid penetrates into the tissue.
The distal end of the tube in this arrangement is preferably so shaped, or provided with a nozzle in such a way, that the hole formed in the tissue during injection closes of its own accord, without previously allowing any appreciable amount of injected fluid to escape. To achieve this, the diameter of the tube end or the nozzle is preferably very small.
The pump mechanism is preferably so constructed that a desired amount of fluid can be injected as a plurality of small, consecutively injected individual volumes. It is therefore necessary that the pump be able to expel very small volumes of fluid one after another in a relatively short time.
Preferably aiming and/or positioning devices are provided at the distal end of the tube, so that the distal end can be kept at a predetermined distance from the tissue and/or oriented in a predetermined direction with respect to the tissue. Preferably these aiming and/or positioning devices are so constructed that the fluid can be injected into the tissue at an angle of about 30xc2x0 to 60xc2x0. That is, the aiming devices for this case must be so constructed that the person operating the apparatus can estimate the angle at which the nozzle or the tube end is directed toward the surface of the tissue.
For special applications the tube, at least in its distal section, comprises several, in particular two lumina. The pumping mechanisms comprise several individual pumps, in order to inject several, in particular two fluids so that they become mixed. This arrangement is useful, for example, when two-component adhesives such as fibrin adhesive are to be injected.
In a further embodiment of the invention the tube preferably comprises a gas- and/or liquid-return lumen, which opens into the tube at its distal end in such a way that the fluid contained in the tube is prevented from emerging through the distal end. For this purpose it is advantageous to provide a suction device to suck fluid out of the fluid-return lumen, which is substantially permanently in operation. This suction device can, for example, be a suction extractor of the kind often present in an operating theatre.
In a preferred embodiment the tube comprises, at or near its distal end, a section with a single lumen or a nozzle, which both facilitates the conduction of such fluid as emerges and, in case two different fluids are to be expelled, enables them to be mixed while still in the tube or the nozzle.
The tube is preferably made of such material, and is sufficiently resistant to pressure and/or provided with sufficient stiffening means, that a pressure pulse introduced into its proximal end emerges essentially undamped or unchanged from its distal end. In this regard it is also important to choose a material with only slight internal damping. The tube can be so constructed that it allows passage of a pressure pulse in its resonant range, like a wave guide. Astonishingly, it has been shown that a tube with a lumen diameter of about 0.2 mm permits such a pressure pulse to pass substantially unattenuated over a length of about 2 m, with adequate rate of rise and adequate pressure.
Preferably the tube, provided with a nozzle where appropriate, together with a fluid reservoir to store relatively large amounts of fluid to be injected during a prolonged period of use or prolonged surgery, is constructed as a sterile injection unit that can be operated as a unit. This construction makes it possible to prepare and perform an injection with minimal manipulation and in an extremely short time, even during an endoscopic operation for which the need of injection was unforeseen. Here it is especially advantageous for the injection unit to be constructed as an item of equipment to be used only once, so as to ensure that there is no deterioration due to wear and tear (blockages or the like) and that no unsterile units are used.
The injection unit preferably comprises at least part of the pump mechanism. One possibility is to equip the pump mechanism with a membrane, a piston or similar movable element as the pressure-generating component, which closes off the fluid reservoir or an intermediate reservoir in the tube in a water-tight manner. To move the membrane or generate the pressure, there can be provided a (disposable) device that is likewise fixedly attached to the whole unit, but preferably a separate, reusable drive mechanism, which applies to the piston or the membrane an adjustable pumping force. For this purpose a suitable pulse generator is provided.
Preferred embodiments of the invention will be come apparent from the subordinate claims.